Liraglutide is an acylated human glucagon-like peptide-1 (GLP-1) agonist, with a 97% amino acid sequence identity to endogenous human GLP-1(7-37). GLP-1(7-37) represents less than 20% of total circulating endogenous GLP-1. Like GLP-1(7-37), Liraglutide activates the GLP-1 receptor, a membrane-bound cell-surface receptor coupled to adenylyl cyclase by the stimulatory G-protein, Gs, in pancreatic beta cells.
Liraglutide increases intracellular cyclic AMP (cAMP), leading to insulin release in the presence of elevated glucose concentrations. This insulin secretion subsides as blood glucose concentrations decrease and approach euglycemia. Liraglutide also decreases glucagon secretion in a glucose-dependent manner. The mechanism of blood glucose lowering also involves a delay in gastric emptying. GLP-1(7-37) has a half-life of 1.5-2 minutes due to degradation by the ubiquitous endogenous enzymes, dipeptidyl peptidase IV (DPP-IV) and neutral endopeptidases (NEP). Unlike native GLP-1, Liraglutide is stable against metabolic degradation by both peptidases and has a plasma half-life of 13 hours after subcutaneous administration. The pharmacokinetic profile of Liraglutide, which makes it suitable for once daily administration, is a result of self-association that delays absorption, plasma protein binding and stability against metabolic degradation by DPP-IV and NEP.
Liraglutide is marketed in USA under the trade name Victoza® in the form of injection and supplied in multiple dose pre-filled pen injectors. Liraglutide is indicated as an adjunct to diet and exercise to achieve glycemic control in patients with type 2 diabetes mellitus.
Liraglutide for first time disclosed in U.S. Pat. No. 6,268,343. In this patent, Liraglutide precursor is produced by recombinant DNA technology from yeast Sachromyces Cerevisiae and further chemically modified by an addition of a Glu-spaced hexadecanoic (palmitic) acid using solution phase method to produce Liraglutide.
The disadvantage of the above process is the N-terminal of GLP-1(7-37)-OH is not protected, which leads to generation of impurities. Additional purification steps are required to remove these impurities, and makes Liraglutide high cost and not suitable for large scale production.
WO 2013/037266 discloses a process to prepare Liraglutide by solid phase synthesis, following sequential addition of amino acids to the supported resin (Wang or 2-chlorotrityl resin) and thereafter cleaved from resin and de-protection is carried out in two steps.
The disadvantage of the above process is, it leads to impure, crude Liraglutide and it is difficult to purify.
CN 102875665 discloses a process for the preparation of Liraglutide by Fragment coupling. Process of CN '665 involves the use of peptide fragment: Fmoc-Gln(Trt)-Ala-Ala-Lys(N-ε-(Na-Palmitoyl-L-y-glutamyl-OtBu))-Glu(OtBu)-Phe-Ile-Ala-OH in the synthesis of Liraglutide.
The disadvantage of the above process is, it leads to formation of optically impure Liraglutide and it is difficult to purify to its homogeneity.
CN 103145828 discloses a process to prepare Liraglutide by solid phase synthesis, following sequential addition of amino acids to the supported resin.
The disadvantage of the above process is, it leads to impure, crude Liraglutide and it is difficult to purify.
The present inventors have made Liraglutide by the process, which is supposed to be simple and industrially scalable with consistent yields. Further, the Liraglutide obtained by the process of the present invention results in higher yield and purity.
The present invention relates to a process for the preparation of Liraglutide by using two or more suitable fragments (protected) by solid phase peptide synthesis, coupling of the fragments on solid support, concurrent cleavage from the solid support and deprotection of peptide, purification of Liraglutide (crude) on reverse phase HPLC, freeze-drying and isolation of pure Liraglutide.
The use of two or more fragments for preparing Liraglutide according to the present invention leads to a better purity product with low level of impurities.